Automation tools

What are the various automation tools availble in testing? How will you decide on a tool for test automation?

There are quite lot of Automation tools available in market. Notable and reliable tools as follows:
-Winrunner
-HP QuickTest Professional HP 11.0
-Load Runner
-IBM Rational Functional Tester IBM Rational 8.2.0.1
-Rational robot IBM Rational 2003
-Selenium Open source 1.0.10
-SilkTest Micro Focus 2010 R2
-TestComplete SmartBear Software 8.2
-TestPartner Micro Focus 6.3
Decision on which tool to be used for Automation is solely depended on the project requirement. There are few points that need to be considered while selecting the tool:
-Cost of the Software tool which support your platform and technology
-Programming language - Easy to learn and use. This covers:
  - Easy dedugging and logging
  - Test Data Management
  - Reporting Features Failure and Error Logging
  - Re-usability of components and libraries